By April Lanux

Southern Japan was hit by a strong earthquake on Monday in a region that had been the subject of the nation's first ever megaquake advisory last year.

A quake with a preliminary magnitude of 6.9 struck the Kyushu region on Monday, the Japan Meteorological Agency said. The JMA was investigating whether the quake was related to the Nankai Trough, NHK said.

The Nankai Trough, where the Philippine Sea Plate is subducting under the Eurasia Plate at the bottom of the sea off the southwest coast of Japan, produces massive earthquakes around every 100-150 years. Strong quakes nearby are seen as a potential indication that a megaquake could be more likely.

The JMA in August issued a week-long advisory for a "relatively higher chance" of a megaquake as powerful as magnitude 9 after a magnitude-7.1 quake hit the country's southwest.

After Monday's quake, tsunami advisories for waves of a maximum height of 1 metre were issued for the southern prefectures of Miyazaki and Kochi. A 20-centimetre tsunami was later recorded reaching Miyazaki city, public broadcaster NHK reported.

There were no abnormalities reported at the Ikata Nuclear Power Plant in western Japan or the Sendai Nuclear Power Plant in Kagoshima prefecture, NHK said, referring to the two plants nearest to where the quake occurred.

By April Lanux

A magnitude 3.7 earthquake struck just off the coast of San Francisco Friday morning, adding a jolt to millions of residents to their morning routine.

The tremor occurred just after 7 a.m. local time, according to the U.S. Geological Survey. It was felt throughout the Bay Area, as far south as San Jose, according to the USGS shake map.

The epicenter was located about 3 miles northwest of the San Francisco Zoo, placing it just off the coast in the Pacific waters. The USGS says the quake had a depth of about 5 miles.

A 3.7 quake is relatively minor and quakes of that strength are common in Northern California. There were no initial reports of any damage, but the San Francisco Muni transit system reported temporary delays on its subway system so tunnels could be checked for any issues. Regular service was to resume once checks were completed.